Furnace roller



3,070,362 Patented Dec. 25, 1962 3,070,362 FURNACE ROLLER Gloyd H.Young, Ida, Mich., and Carroll Cone, Toledo, Ohio, assignors toMidland-Ross Corporation, Toledo, (bhio, a corporation of Ohio FiledMar. 2, 1961, Ser. No. 92,863 4 Claims. (Cl. 263-6) This inventionpertains to a furnace roller. More particularly, this invention relatesto a furnace roller suited for supporting and turning a strip of sheetmetal as it passes through a continuous heating furnace. The inventionmay, in general, be considered to be directed to an improvement infurnace rollers of the type described in United States Patent 2,932,497to W. H. Dailey, lr. et al.

The continuous metallurgically heat-'treatment of a strip of sheet metalis normally accomplished by conveying the strip in a series of verticalpasses or strands through each of several treating zones, the transitionof the strip from one pass to another being accomplished by means of aturning roller. Normally a furnace for accomplishing this heat treatmentincludes a heating zone, a holding zone, and several -cooling zones. Atypical example of such a treating unit is illustrated at page 76 of theFebruary 1957 issue of Iron and Steel Engineer.

The design of a turning roller for the heating section of a continuousstrip processing furnace 4normally involves several problems notinherent in the design of rollers for other stages of the furnace. Tobegin with, the rollers in the heating section will normally be of anappreciably greater diameter than rollers in lthe other furnace zones.The larger diameter is required to provide suilicient clearance betweenadjacent strip passes for insertion of radiant heating tubestherebetween, such clearance normally being equal to the rollerdiameter.

Secondly, the furnace zone rollers tend to receive great quantities ofheat which tends to pass through the roller to the bearings in which theroller is mounted. This problem of transfer of heat through the rollerto the bearings, in addition to the fact that it adversely affectstemperature uniformity within the furnace, is a problem which can leadto lubrication difliculties and even to premature bearing failure. Suchproblem can be combatted by means of certain heat flow retardingexpediencies disclosed in the aforementioned APatent 2,932,497 toDailey, I r. et al.

Among the heat flow retarding expediencies utilized by Dailey, lr., etal. is the expediency of constructing the ends of the roller withtapered trunnions at each end thereof. Such a construction permits asubstantial reduction in the size of the ports in the fur-nace wallthrough which the ends of the roller pass and therefore helps todecrease heat transfer from the furnace through the roller. -As anadditional heat liow retarding expediency it was suggested to line thetapered trunnion-s with refractory, which is normally accomplished byfilling the trunnions with a cast refractory insert.

The use of refractory filled roller trunnions has heretofore met withsome success in lower speed strip processing furnaces. In recent years,however, there has been a demand for higher -speed strip processing,with furnace users now requiring equipment to process strip at stripspeeds in excess of 2000 f.p.m. whereas the maximum limit on stripspeeds was 1000 rf.p.m. but a few years ago. Rollers constructed withrefractory filled tapered trunnions have not been well suited for higherspeed strip processing because the mode of inserting such refractory,which normally comprises packing a wet castable refractory into placeand allowing it to set, inherently makes it diicult to balance therollers.

In any strip processing furnace it is necessary to carefully balance thefurnace rollers to avoid roller vibration which can reduce roller lifeand cause damage to the `bearing and drive elements. A roller for ahigher speed furnace must be more carefully balanced than a roller for alower speed furnace since the problem of vibration becomes more acute athigher speeds. The use of refractory insulation not only makes it morediflicult to lbalance the rollers but also makes it more diflicult tomaintain balance because of the tendency of such material to deteriorateand to be displaced, a tendency which is also greater at higher speedsby virtue of the greater centrifugal force to which the refractory issubjected.

Accordingly, it is the object of this invention to provide novel meansfor retarding the passage of heat through the trunnions of a furnaceroller, said means comprising at least one (l) and preferably aplurality of thin metal plates mounted within said trunnion in such amanner that a substantial portion of the faces of each plate are innonthermal conducting relationship with any other plate and/ or otherportions of the roller, such plates therefore being adapted to serve asradiation shields.

For a further consideration of what we believe to be novel and ourinvention, attention is directed to the following portion of thespecification, the drawing, and the appended claims.

In the drawing:

FIGURE l is a fragment of a sectional elevational view of a furnacehaving rollers constructed in accordance with this invention.

FIGURE 2 is a partially sectional view of a roller embodying theinvention.

As is shown in FIGURE l, a furnace heating chamber 11, which is dened byrefractory walls 12 and metal binding 13, is provided for heating astrip of sheet metal 14 which is passed to and fro through heatingchamber in a plurality of vertical passes. Strip 14 is heated primarilyby thermal radiation from radiant heating tubes 15 which are mountedintermediate adjacent passes of strip.

A number of furnace rollers 16 are located within the -furnace tosupport strip 14 therein and to provide .for the turning of the stripfrom an upwardly traveling pass to the next -downwardly traveling pass.It is to be understood that like rollers are located near the bottom ofheating chamber 11 to provide for the turning of the strip from adownwardly traveling pass to the next upwardly traveling pass. Locatedintermediate rollers 16 and radiant tubes 15 are a number of bailies 17whose function it is to block direct thermal radiation from the radianttubes to the rollers, thereby serving to combat the problems of heatdissipation associated with such rollers.

The construction of furnace roller 16, per se, is shown in more detailin FIGURE 2 wherein roller 16 is constructed of a cylindrical rollerbody 21 having tapered trunnions 22 attached to the ends thereof. Rollerbody 21 and trunnions 22 are assembled by inserting a trunnion in eachend of the roller body, a bored portion 23 being provided in each end ofroller body 21 for receiving a trunnion. Trunnions 22 are then securedto roller body 21 as by means of a weld 24. A bearing shaft 25 islocated at each end of the roller to provide for mounting of the roller,which may be accomplished in accordance with the teachings of Dailey,Ir. et al. Patent 2,932,497.

To retard the tlow of heat from the roller body 21, which is locatedwithin the heating chamber, to bearing shafts 25, which are locatedoutside of the heating chamber, insulating means 26 are provided insidethe trunnions. The insulating means heretofore utilized by priorartisans, as was previously mentioned, normally comprised a castrefractory insert. Such construction was quite effective insofar asinsulating properties are concerned, but was, however, subject tomechanical deterioration caused by heat, vibration, and centrifugalforce, a problem which became quite severe in higher speed furnaces. Toeliminate the problems associated with refractory filled trunnions wehave devised insulating means which comprises at least one (l) andpreferably a plurality of thin metal plates such as plates 27 and 28`which are inserted within trunnions 22, extending generallyperpendicularly with respect to the axis of the trunnion. Plates 27 and28 are adapted to serve as thermal radiation shields which requircs thatat least a substantial portion of both faces of each plate be innon-conducting relationship with the other plate and/or any portion ofthe roller.

Metal plates 27 and 28, which are of different diameters to insure thatthey will be maintained in spaced apart or non-heat conductingrelationship with respect to each other, are attached to the respectivetrunnions by aixing the outer periphery of the plates to the innersurface of a trunnion, as by means of tack welds 31 and 32. The centersof metal plates 27 and 28 are secured with respect to each other byafiixing them to a central spindle 33 which also serves as a spacer.When additional insulating effect is desired the narrower cooler portion22a of each trunnion may be filled with a suitable insulating material34 such as rock wool. Insulating material 34, when used, can be retainedin place by means of a metal plate 3S which is similar to metal plates27 and 28 but does not function as a true radiation shield because it isin thermal conducting relationship with insulation 34.

The means for insulating a furnace roller trunnion described above,which comprises two (2) radiation shields 27 and 28 located therein,approaches the insulating efectiveness of a refractory filled trunnionwhile at the same time avoiding the mechanical problems associatedtherewith. It is to be noted that any number of radiation shields may beused depending on the degree of insulating effectiveness desired, eachradiation shield, in theory, serving to block about one-half of the heatradiated to it.

The best mode known to us to carry out this invention has been describedabove in terms sufficiently full, clear, concise, and exact as to enableany person skilled in the art to make and use the same. It is to beunderstood, however, that certain modications of the above describedmode of practicing this invention can be made by a skilled artisanwithout departing from the scope of the invention which is defined onlyby the appended claims.

We claim:

l. A furnace roller comprising, in combination: a cylindrical body; atapered trunnion attached to each end of the cylindrical body; a firstthin circular metal plate disposed within each trunnion, said metalplate being disposed substantially perpendicularly to the axis of thetrunnion with its periphery attached to the inner surface of thetrunnion and having a substantial portion of each face in non-thermalconducting relationship with any other portion of the roller; and asecond thin circular metal plate being disposed within each trunnion ata distance from said first plate and nearer to the cylindrical body thansaid first plate, said second plate having a diameter greater than thediameter of the first plate and being disposed generally parallel to thefirst plate with its periphery attached to the inner surface of thetrunnion and defin fr ing a substantially enclosed insulating volumewith the trunnion and the first plate.

2. Apparatus according to claim l and further compris ing a spindledisposed within the trunnion axially thereof and attached to the centersof the first and second thin circular metal plates.

3. A furnace roller comprising, in combination: a cylindrical body; atapered trunnion attached to each end of the cylindrical body; a firstthin circular metal plate disposed within each trunnion, said metalplate being disposed substantially perpendicularly to the axis of thetrunnion with its periphery attached to the inner surface of thetrunnion and having a substantial portion of each face in non-thermalconducting relationship with any other portion of the roller; a secondthin circular metal plate being disposed within each trunnion at adistance from said first plate and nearer to the cylindrical body thansaid first plate, said second plate having a diameter greater than thediameter of the first plate and being disposed generally parallel to thefirst plate with its periphery attached to the inner surface of thetrunnion and defining a substantially enclosed insulating volume withthe trunnion and the first plate, insulating material disposed withinthe trunnion at a distance from the first plate and further away fromthe end of the cylindrical body to which the trunnion is attached; and athird thin circular metal plate intermediate said first plate and saidinsulating material having a face abutting against said insulatingmaterial and being adapted to retain said insulating material, saidthird plate having a lesser diameter than said first plate and beingdisposed generally parallel to the first plate with its peripheryattached to the inner surface of the trunnion and defining a secondsubstantially enclosed insulating volume with the trunnion and the firstplate intermediate the insulating material and the first insulatingvolume.

4. A furnace roller comprising, in combination: a cylindrical body; atapered trunnion attached to each end of the cylindrical body; a firstthin circular metal plate disposed within each trunnion, said metalplate being disposed substantially perpendicularly to the axis of thetrunnion and having a substantial portion of each face in non-thermalconducting relationship with any other portion of the roller; insulatingmaterial disposed within the trunnion at a distance from the first plateand further away from the end of the cylindrical body to which thetrunnion is attached; and a second thin circular metal plateintermediate said first plate and said insulating material having a faceabutting against said insulating material, and being adapted to retainsaid insulating material said second plate having a lesser diameter thansaid first plate and being disposed generally parallel to the firstplate with its periphery attached to the inner surface of the trunnionand defining a substantially enclosed insulating volume with thetrunnion and the first plate.

References Cited in the file of this patent UNITED STATES PATENTS1,840,661 Fahrenwald Jan. 12, 1932 1,871,937 Wilson Aug. 16, 19322,932,497 Dailey et al Apr. 12, 1960

